The invention relates to improvements in material removing machines in general, and more particularly to improvements in devices for releasably mounting tools in material removing machines. Still more particularly, the invention relates to improvements in tool mounting devices which can be utilized with advantage in underground mining machines, for example, in so-called longwall shearing and/or heading machines.
It is often necessary to cool the tool which is used in a mining machine to remove material from the mine face and/or to cool the path or track which is cut into rock, coal or other material by a moving bit or another suitable tool, e.g., a tool of the type described and shown in European Pat. No. 0 067 145 granted to Zitz et al. The patent proposes to install in the tool holder a nozzle adjacent the bit so that the stream of water or another coolant which is used in the material removing machine can be directed against the working end of the tool or in another desired direction. In order to avoid waste of coolant, the patentees propose to mount the tool in its holder in such a way that the rear end of the tool shank initiates the admission of coolant to the nozzle when the tool is in the process of removing material, e.g., in an underground excavation. The purpose of the coolant is manifold. Thus, the coolant can impinge upon the tip of the tool and/or upon the material to be cut, and it can also serve to prevent the development of excessive quantities of dust which could affect the comfort and health of workers in an underground excavation. The tool has limited freedom of axial movement in its holder and is depressed in response to engagement with the material to be removed whereby the rear end of the tool shank initiates the admission of coolant to the nozzle which is adjacent the working end of the tool and is mounted in the tool holder.
The nozzle which is used in the tool holder of Zitz et al. is provided with external threads which mate with the threads in a tapped bore of the tool holder. Reference may also be had to page 3 of the August 1985 edition (No. 117) of the German-language publication entitled "Kurznachrichten aus Bergtechnik und Kohlenveredelung". A drawback of such mounting of the nozzle is that mechanical stresses to which the nozzle is subjected in actual use of the material removing tool are very pronounced so the external threads of the nozzle and/or the internal threads of the tool holder are likely to be damaged. Consequently, the nozzle cannot be readily removed from its holder which creates many problems and can cause lengthy interruptions of operation of the machine which employs such tool holders and nozzles.
Commonly owned earlier filed German patent application No. P 39 02 222 discloses a tool holder which constitutes a modification of the tool holder of Zitz et al. The difference is that the tool holder of the earlier filed commonly owned patent application contains a valve which can be opened to admit coolant to the nozzle in response to axial displacement of the tool but the valve is not operatively connected to the shank of the tool. Instead, the tool holder contains a reciprocable pusher which can be moved by the head of the material removing tool to thereby open the valve and admit coolant to the nozzle when the working end of the tool engages the material of a mine face. An advantage of such mode of controlling the admission of coolant to the nozzle is that the exact length of the tool shank is of no consequence.
Presently known holders for material removing tools which must be cooled during engagement with a mine face or the like exhibit certain additional drawbacks. For example, proper sealing of the nozzle in the tool holder often presents many problems, especially if the nozzle is mounted in two separable parts of the tool holder. German Pat. No. 36 30 636 to Beyer discloses a material removing tool mounted in a holder adjacent a nozzle which must be tilted in response to axial displacement of the tool as a result of penetration into the material of a mine face or the like. Tilting of the nozzle establishes communication between the inlet of the nozzle and a coolant-supplying channel in the tool holder. Such tiltability of the nozzle creates problems in connection with proper sealing of the path for the flow of coolant from the source, through the holder and into the tilted nozzle. The latter is tilted by a leaf spring which is carried by the shank of the tool and is flattened in response to rearward movement of the tool to thereby change the orientation of the nozzle.